The present invention relates generally to data networking and, more specifically, to a method and system for automatic generation of route distinguishers for Virtual Private Networks (VPNs).
The rapid growth of the Internet and the widespread deployment of networks built around the Internet Protocol suite are creating a demand for new capabilities in IP (Internet Protocol) networks. MultiProtocol Label Switching (MPLS) provides a number of powerful capabilities such as traffic engineering, etc. MPLS is an IETF (Internet Engineering Task Force) initiative that integrates Layer 2 information about the network links (bandwidth, latency, utilization) into Layer 3 (IP) within a particular autonomous system in order to simplify and improve IP packet exchange. Service providers with an MPLS/IP backbone may provide VPNs for its customers, as described in RFC 2547 (“BGP/MPLS VPNs”, E. Rosen et al., March 1999), which is incorporated herein by reference in its entirety. Virtual Private Networks serve as network overlays on IP network infrastructures.
FIG. 1 illustrates an example of a provider network in communication with two customer networks, vpnA and vpnB. The provider network includes a plurality of provider routers (P) and provider edge (PE) routers. The VPNs include customer edge (CE) routers. Each VPN is associated with one or more VPN routing/forwarding instances (VRFs), which define the VPN membership of a customer site attached to a PE router. A VRF consists of an IP routing table, a derived Cisco Express Forwarding (CEF) table, a set of interfaces that use the forwarding table, and a set of rules and routing protocol parameters that control the information that is included in the routing table. Packet forwarding is performed based on label information within the MPLS core network, as is well known by those skilled in the art.
In MPLS VPN configuration of routers, the operator needs to define a route distinguisher (RD) associated with a VPN. A route distinguisher is an address qualifier used within an internet service provider's MPLS network. The route distinguisher is assigned by the provider to a VPN and used to distinguish VPN routes of separate customers who connect to the provider. The route distinguisher is an 8 byte field prefixed to the customer's IPv4 address. The resulting 12 byte field is a unique VPN-IPv4 address. As described in RFC 2547, the 8 byte route distinguisher comprises three fields: Type Field (2 bytes), which determines the lengths of the other two fields, as well as the semantics of the administrator field; Administrator Field, which is typically the 4 byte autonomous system (AS) number of the provider; and Assigned Number Field, which is assigned by the provider. The AS number and the Assigned Number make the VPN-IPv4 address globally unique.
The route distinguisher is used by edge routers to identify which VPN a packet belongs to. Within an MPLS network, a PE router is configured to associate each route distinguisher with routes that lead to a particular CE router. The route distinguisher used to generate the VPN-IPv4 prefix is specified by a configuration command associated with the VRF on the PE router. Configuration steps performed on a router include assigning a route distinguisher, configuring import of route targets, and configuring export of route targets.
Many Enterprise customers are deploying MPLS VPNs. However, one problem is that it is necessary to simplify the configuration of MPLS VPNs on the router. Instead of having all of the information on the VRF (four lines of configuration commands), it is desired to hide the configuration complexity and instead handle this detail behind the scenes so that the configuration detail has only one line. In order for this to be done, however, the route distinguisher must be autogenerated from the VPN name.
There is, therefore, a need for a method and system for automatically generating from a VPN name, a unique route distinguisher that can be used to build full mesh VPNs with less configuration detail.